Magnet-core for dynamo-electric machines.



PATENTED SEPT. l, 1903.

W. B BURROW.

MAGNET GORE FOR DYNAMO ELECTRIC MACHINES.

AAAAAAAAAAAAAAAAA UG.1'4. 1902.

N 0 M 0 D E L.

UNITED STATES Patented September 1, 1903.

PATENT OFFICE.

WVALTER l3. BURROXV, OF NORFOLK, VIRGINIA.

SPECIFICATION forming part of Letters Patent No. 737,576, dated September 1, 1903.

Application filed August 14, 1902. $erial No. 119,658. (No model.)

To aZZ whom, it may concern:

Be it known that I, WALTER B. BURROW, a citizen of the United States, residing at Norfolk, in the county of Norfolk and State of Virginia, have invented certain new and useful Improvements in Magnet-Cores for Dynamo- Electric Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it ap pertains to make and use the same.

My invention relates to field-magnet cores or pole-pieces for dynamo-electric machines, and has for its object the means of increasing and decreasing the amount of metal of the cores and the concentration of the magnetic lines of force to one or more points of the core, as will be hereinafter described.

Referring to the drawings, Figure 1 is an elevation of the yoke or frame of the dynamo electric machine with the cores in position and without the field-exciting coils. Fig. 2 is a section through one of the cores on the line 1 2 in Fig. 3. Fig. 3 is a part of the yoke or frame and one of the cores and shows the triangular openings partly filled up when the armature is to rotate from right to left or counter-clockwise. Fig. 4: is the same view as Fig. 3, with the exception that the righthand side of the triangular opening is filled up when the direction of rotation of the armature is to be from left to right, or clockwise. Fig. 5 is an elevation of one of the wedge-shaped metal triangles or blocks for filling up the openings in the cores. Fig. 6 is the back or width of one of the wedge-shaped triangular blocks.

In the drawings, in which like referenceletters indicate similar parts in all the views, A is the field-magnet yoke or frame, which supports the cores suitably spaced aroundits inner circumference in the usual manner.

B represents the field-magnet cores or polepieces having triangular openings through them parallel to the axis of the dynamo.

' 0 represents the triangular-shaped openings through the cores and are placed at right angles to the direction of rotation of the armature or parallel with the armature-shaft. As shown in the drawings, the openings take the form of isosceles triangles and are adapted to flat or rectangular cores; but they assume the shape of an equilateral triangle when the cores are of a circular cross-section, the shape of the openings depending on the width of the cores and the effect desired.

D is a thin part or bridge at the lower ends of the cores, formed by the base or shorter side of the triangles, making a line tangent to the armature circle or curve of the corefaces, as shown near D. The bridge D unites the two parts of the core and forms a part thereof and does not separate the two sides into half by an air-gap.

G represents removable soft-iron triangular or wedge-shaped blocks and are for the purpose of filling up from one-quarter to onehalf the openings 0 in the cores B, according to the effect desired and the direction of rotation, as shown in Figs. 3 and 4:.

G in Figs. 5 and 6 represents the backs or widest parts of the wedge-shaped blocks or triangles.

The openings 0 in the cores B besides rendering the dynamo lighter also allow for proper ventilation for the field-coils. They also reduce the armature reaction and, consequently, sparking, asthe field strength governs such tendency to flash or spark at the commutator and for its regulation requires the shifting of the brushes to a point where the effect is less violent. Where there is an opening in the-cores, the difficulty is overcome and with it the cross-magnetizing effect which distorts the magnetic flux, according to the degree of load on the machine. With an opening or bridged gap the magnetic saturation is concentrated at the divided portion, the degree of which can be varied by altering the amount of the magnetic material by closing up the openings more or less with the wedge-shaped blocks and placing them at either side of the cores, according to the direction of rotation of the armature. As already described, when the cores are perforated or open the magnetic saturation is concentrated to the split or divided portion and is greatest in that part in which the armature rotates and remains fixed, while that on the opposite side, of less magnetic material, increases with the magnetization. In such cases the angle of lead of the commutatorbrushes remains constant from no load to a reasonable overload. r

The soft-iron wedge-shaped blocks are made of low carbon or wrought-iron or similar metal, which takes up as little residual magnetism as possible.

Having described my invention, what I claim, and desire to secure by Letters Patent, 1s

1. A field-magnet core or pole-piece for dynamo-electric machines, having an isosceles triangular-shaped opening through the said core, parallel with the axis of rotation of the armature, the said opening occupying from one-eighth to one-half of the solid contents of the core, and the base of the said triangular opening near the curve of the core-face, as described.

2. A metallic field-magnet core for dynamoelectric machines having a triangular-shaped opening or perforation through the said core, and a thin metallic bridge integral with and joining the two sides of the core near its face, and a detachable metallic triangular-shaped block or wedge to fill half of the opening, the said Wedge conforming to and filling either side of the triangular opening in the core, according to the direction of rotation of the armature, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WALTER B. BURROW.

Witnesses:

J R. BoNDs, A. H. ROGERS. 

